生物谷报道:日本科学家发现,存活在人体内脏中使人生病的某些致病细菌可能是由生活在海洋深处、能经受极限环境考验的它们的始祖进化而来。
日本科学家在最新一期美国《国家科学院学报》上发表文章说,他们分析了两种致病内脏细菌的基因排序,并将其与两种类型非常接近、但生活在海底深处的无害细菌进行比较。
科学家们发现,内脏细菌和海底的细菌有着许多相似的基因,这些基因使其能够在极端环境下生长。它们还具有极少量的DNA修复基因,允许出现频繁的突变,并快速适应不断变化的环境以及共生宿主的免疫反应。
科学家在文章中说,这种特性使得内脏细菌能够“不断传染”。
科学家所选取的这两种细菌分别是导致内脏溃疡的螺旋菌及造成出血性腹泻的弯曲杆菌。
在深海中发现的是两种变形细菌——Sulfurovum和Nitratiruptor,它们生活在非常恶劣的环境中,只有最强壮的微生物才能在那里存活下来。(新华网)
原始出处:
Published online before print July 5, 2007, 10.1073/pnas.0700687104
PNAS | July 17, 2007 | vol. 104 | no. 29 | 12146-12150
Deep-sea vent -proteobacterial genomes provide insights into emergence of pathogens
Satoshi Nakagawa,, Yoshihiro Takaki, Shigeru Shimamura, Anna-Louise Reysenbach¶, Ken Takai, and Koki Horikoshi,
Subground Animalcule Retrieval (SUGAR) Program and Extremophiles Research Program, Extremobiosphere Research Center (XBR), Japan Agency for Marine–Earth Science and Technology (JAMSTEC), 2-15 Natsushima-cho, Yokosuka 237-0061, Japan; and ¶Department of Biology, Portland State University, Portland, OR 97201
Edited by Rita R. Colwell, University of Maryland, College Park, MD, and approved June 7, 2007 (received for review January 25, 2007)
Deep-sea vents are the light-independent, highly productive ecosystems driven primarily by chemolithoautotrophic microorganisms, in particular by -Proteobacteria phylogenetically related to important pathogens. We analyzed genomes of two deep-sea vent -Proteobacteria strains, Sulfurovum sp. NBC37-1 and Nitratiruptor sp. SB155-2, which provide insights not only into their unusual niche on the seafloor, but also into the origins of virulence in their pathogenic relatives, Helicobacter and Campylobacter species. The deep-sea vent -proteobacterial genomes encode for multiple systems for respiration, sensing and responding to environment, and detoxifying heavy metals, reflecting their adaptation to the deep-sea vent environment. Although they are nonpathogenic, both deep-sea vent -Proteobacteria share many virulence genes with pathogenic -Proteobacteria, including genes for virulence factor MviN, hemolysin, invasion antigen CiaB, and the N-linked glycosylation gene cluster. In addition, some virulence determinants (such as the H2-uptake hydrogenase) and genomic plasticity of the pathogenic descendants appear to have roots in deep-sea vent -Proteobacteria. These provide ecological advantages for hydrothermal vent -Proteobacteria who thrive in their deep-sea habitat and are essential for both the efficient colonization and persistent infections of their pathogenic relatives. Our comparative genomic analysis suggests that there are previously unrecognized evolutionary links between important human/animal pathogens and their nonpathogenic, symbiotic, chemolithoautotrophic deep-sea relatives.
-Proteobacteria | comparative microbial genomics | deep-sea hydrothermal vent | pathogenesis | symbiosis